So when Anderson’s longtime collaborator, Oscar-winning costume designer Mark Bridges (The Artist) began work, Day-Lewis already knew how the exacting Woodcock would dress.

“Daniel knows the world of bespoke,” Bridges told Vanity Fair, pointing out the actor’s background—he grew up in the affluent neighborhood of London's Kensington, as the son of poet Cecil Day-Lewis. “I’ve discovered, while studying for this film and of course working with Daniel, that it’s not unusual for men of a certain status in England to be concerned and aware of their wardrobes. A gentleman would think about the placement of a buttonhole or a kind of fabric.”

Day-Lewis plucked costume inspiration from people familiar to him, choosing Reynolds’s suits, for example, from Anderson & Sheppard, the Savile Row clothing house established in 1906 that dressed Day-Lewis’s father (as well as Cary Grant and Prince Charles). When Bridges and Day-Lewis went to Anderson & Sheppard during one of their wardrobe quests, Bridges noticed that Day-Lewis’s own father, wearing his Anderson & Sheppard best, was featured in a book inside the historic store.

“Daniel would refer to people in his life, like we knew gray-flannel slacks would be right because his grandfather always wore the gray flannel with his country clothes,” Bridges said. ”He knew people who wore their Anderson & Sheppard country blazers“—as Reynolds does at his country house—“for years and years and years. There was a lot of him bringing his knowledge of that English wear to the table, and then us working together to make the pieces feel right for our film and to make sure they were photogenic.”

On several days, when Day-Lewis had breaks in his schedule, he and Bridges went shopping together in Mayfair—meeting at Drake’s haberdashery or Hilditch & Key to peruse ties. At Budd Shirt Makers, Day-Lewis handpicked a pair of lavender pajamas off the rack—which his character wears in several memorable scenes—as well as a blue pair with red piping. Bridges called the shopping excursions “really fun . . . a highlight of the process.”

Day-Lewis, as Reynolds, was drawn to colors in the lavender and purple family—fitting, considering that the character is crafting the House of Woodcock’s spring collection during the movie. In addition to choosing the aforementioned pajamas and a gray-lavender bow tie, Day-Lewis selected magenta socks from the historic Gammarelli store in Rome, which is famous for outfitting the Pope and Vatican clergy.

The wardrobe that Bridges and Day-Lewis assembled for Reynolds was placed into the character’s closet in the London townhouse where Phantom Thread filmed. Once shooting began, Bridges entrusted Day-Lewis, as Reynolds, with assembling his outfits for scenes.

“I had been with him making all the decisions for the clothes, so I felt like if he wanted to put together certain combinations because that’s what he was feeling at the time, then that would be fantastic and unique and help his process,” explained Bridges. “He would go in [his character’s closet] and emerge in what he was feeling at that given time for the scene.”

Day-Lewis assembled his wackiest combination—a tweed jacket over lavender pajamas—for a scene in which his character is appalled to discover that Alma [Vicky Krieps] has disrupted his precise schedule and sent his staff home so that she could surprise him with a home-cooked dinner. A creature of routine who is horrified by this spontaneity, Reynolds slinks downstairs, expressing his displeasure sartorially.

“Paul and I just were really, really pleased that that’s what rambled down the stairs for that scene,” said Bridges, laughing, as he remembered the crew’s shock at seeing this particular wardrobe combination. “It was really fantastic. It’s just a personal choice of Reynolds on how he wants to approach this dinner.”

Vicky Krieps and Daniel Day-Lewis in Phantom Thread.

By Laurie Sparham/Courtesy of Focus Features.

Given how method Day-Lewis’s process is, the actor also had a small hand in designing the couture gowns his character creates for a society fashion show.

“Daniel as Reynolds Woodcock the designer wanted to have a certain authorship to some of the House of Woodcock creations,” explained Bridges. “Oftentimes that would take place with him choosing a color or choosing a fabric or a fabric combination. He would choose that, and it would be like, ‘O.K., thanks Reynolds.’ We would only get a few minutes with him. Then he would go and work on the enormous amount of work that he had to do in front of camera. [My costume department] would take it from there. We would do the fitting. We would make sure the construction was right, the fit was right, the delivery date was right. He came away from it feeling some connection to it as a couturier would of one of their creations.”

“There were a couple of fittings that he came in on as well,” added Bridges, including those for Gina McGee, who plays Countess Henrietta Harding. “It was all of us in the fitting room together: me, the cutter, Daniel, Henrietta, and a couple of assistants. . . . I think it was to have the back and forth with that actress who was going to be playing his client and then, also, feeling an element of authorship there, that was so important to his performance.”

For Alma’s character, Bridges telegraphed her transformation through costume—from the homemade dress she wears on her first date with Reynolds, to the more glamorous couture she wears once she is swept up into the House of Woodcock. (Though in the scenes where she rebels against Reynolds’s strict routine, Bridges dressed Alma in clothing that opposed Reynolds’s aesthetic.) For Reynold’s sister and business partner Cyril, played by Lesley Manville, Bridges took a cue from his research of 1950s fashion houses.

“The concept of Cyril’s costume came from reading about Cristóbal Balenciaga's house and how his main saleswoman had an unofficial uniform—navy-blue dress, pearls, and hair tightly put back. I had originally wanted the navy blue on Cyril, but Paul wanted to play up [Manville’s] fair English skin and blue eyes, so we settled on charcoal,” said Bridges, crediting bespoke London tailor Thomas von Nordheim for creating Cyril’s incredible, structured dresses. “With Lesley, I wanted things that seemed elegant and easy and, because she is a very petite woman, to have an unbroken line that would be lengthening on her. She wanted to wear a higher heel, which I think makes her glide in a little more sexy manner, or authoritarian as well.”

To ensure that everyone within the House of Woodcock represented the perfectionism of its founder, Bridges said that the Phantom Thread cast underwent rigorous costuming sessions: “Lesley likes to joke that she had more hours of fittings than she had shooting days.”